Mixing apparatus for concrete or the like



Oct. 30, 1962 A. MUCKEL ETAL MIXING APPARATUS FOR CONCRETE OR THE LIKE File'd Dec. 29, 1958 f F W 7 m a @i v we 9 V. E /W MM I M y T5 5 3 mfi m f v \Ww m W F a 5 W J5 r fill. H1] 1 x rm United States Patent 3,061,283 1 MIXING APPARATUS FOR CONCRETE OR THE LIKE Alfred Miickel, Neustadt an der Weinstrasse, and Hermann Pfaif, Hassloch, Pfalz, Germany, assignors t0 Internationale Baumasehinenfabrik Aktiengesellschaft, Neustadt an der Weinstrasse, Germany Filed Dec. 29, 1958, Ser. No. 783,389 Claims priority, application Germany Jan. 9, 1958 3 Claims. (Cl. 259178) The present invention relates to mixing apparatus for use in the preparation and mixing of concrete or the like. More in particular, the invention relates to mixing apparatus in which the mixer components are operated within a vertically disposed cylindrical mixing chamber and comprise a readily interchangeable driving gear driven from an external prime mover and reduction gear for converting the speed of the prime mover to the reduced speed of the mixing elements and of the charging hoist or discharging means associated with the mixer.

Many forms of construction of apparatus for the mixing and preparation of materials of different size of granule and of different consistency, such as for example those which are used for the preparation of concrete, are well known and these in turn are based on many different operating principles. The so-called hopper or barrel mixers and the so-called forced feed mixers are the most important types of mixers in common use and, due to the pressure of the increasing requirements as to economy, the latter are coming more and more into prominence.

One embodiment of a forced feed mixer, wherein the materials to be prepared are placed in an upright cylindrical mixing chamber and are subjected therein to the operation of suitably constructed mixing devices may be regarded as particularly advantageous. When, as is frequently the case, such mixing apparatus is used in the preparation of concrete on building sites, it is generally subjected to extremely severe operating conditions which may frequently lead to the breakdown of the driving gear. Stopping of the entire mixing apparatus may result in impossible conditions in the progress of the work of laying the concrete, particularly on large building sites where it is necessary for very large quantities of concrete to be prepared continuously and where a rather long breakdown in the feeding of fresh concrete can lead to undesirable imperfections in the condition of the masonry of the building under construction. Consequently, in order" to keep any breakdowns as short as possible, it is especially necessary in such work to select a driving mechanism which per se is robust but also, when it breaks down, can be exchanged in an extremely short time.

Furthermore, most mixing devices require a charging hoist for the feed of material to the mixer and a building winch or the like for the removal of the prepared concrete mix from the mixer.

In constructing the driving gear it is important therefore to bear in mind that the driving gear should also be capable of use in the simplest manner possible for operating the charging hoist or the like. Finally it is only necessary to ensure that electric power is available on all sites for feeding an electric motor which, per se, is the most suitable driving means. of the mixer must be obtained from other power sources such as a diesel engine. In consequence care must be taken to ensure that the power source can be exchanged very rapidly without any complications.

In a particular known embodiment of the forced feed mixer, the entire drive is arranged in a cylindrical center space of the mixing chamber which may otherwise be regarded as dead and useless space as far as the mixing operation is concerned. The mechanism located in this In many cases the drive.

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space, with its drive shaft upright, drives the mixing instruments, which prepare the materials to be mixed in the cylindrical mixing chamber with the aid of a plate or cup-shaped intermediate member which covers the center space and to the periphery of which the mixing instruments are secured.

In another known embodiment, the inner space is occupied merely by a reversing gear having two bevel gears, which produce a predetermined degree of speed reduction. However, this is far from sufficient to reduce the speeds of the usual drives either of an electric motor or of an internal combustion engine to the speeds necessary for the mixers concerned. Consequently a separate transmission is required outside the confines of the mixer. 1

It is, therefore, an object of the invention to provide a mixing device, especially for the preparation of concrete or the like, in which the above desiderata are taken into account and which in particular offers a compromise of the best possible kind in regard to the individual operations involving the conflicting requirements indicated.

It is a particular object of the invention to provide a mixing apparatus having vertically and centrally disposed driving gear which is readily accessible and interchangeable.

It is a further object of the invention to provide a mixing apparatus which is compact in arrangement and size, which can be driven by different prime movers and which is economical to construct and to operate.

In accordance with the present invention a mixing device constructed in a conventional manner as a forced feed mixer with a vertically disposed cylindrical mixing chamber in which the gear mechanism which is driven by an external prime mover or power source and serves to reduce the generally identical or approximately identical speeds of the driving motors, is arranged to be easily exchangeable in a central position in the middle of the dead space of the mixer at a speed necessary for the mixing instruments and the feed hoist.

Preferably the driving gear comprises a worm gear arranged on a vertical shaft, driven by the driving motor by way of a worm, and at its upper part the vertical shaft drives the mixing devices through a planetary gear. At its lower part the shaft directly drives a cable drum for the charging hoist which drum is provided with conventional clutch and braking means.

Further details and objects of the invention will become apparent from the following specification and by reference to the accompanying drawings which illustrate one embodiment of the invention by way of example and in which:

FIGURE 1 is a vertical section taken through a mixer showing the drive arranged in accordance with the present invention,

FIGURE 2 is a horizontal section taken through the planetary gearing of the drive,

FIGURE 3 is a horizontal section taken through the cable drum of the drive.

In the construction illustrated the mixing container of the forced mixer is constructed in conventional manner as an upright outer cylinder 1 and an inner cylinder 1a, which cylinders are supported on a support plate 1b. In an annular cylindrical chamber 2, located between the inner cylinder 1a, which encloses a center space 5, and the wall of the cylinder 1, which is used for the mixing operation, are located a number of arms 3 with rotating, resiliently journalled staggered mixing devices 4. The arms 3 are secured to radially extending means 3a secured to shaft 16 at the upper end thereof. The center space 5 defined by inner cylinder 1a which in any case is useless as part of the mixing chamber is utilized to accommodate driving gear 6 which is fitted therein in such manner as to be readily removable therefrom and replaceable. The drive is obtained from any desired external power source. I

In the embodiment illustrated said source is constituted by an electric motor 7 which drives the mechanism by way of a shaft 8 connected at one end by a flange or other coupling 9 to the electric motor and, at the other end, by a flange or other coupling 1% to the driving gear. Any other desired source of power, such as a diesel engine for example may, however, be used instead of the electric motor 7.

The rotary speed of the shaft 8 is reduced by means of a worm (not shown) and a worm wheel 11 in engagement therewith. Through the intermediary of a gear wheel 12 on a hollow shaft or sleeve 13, and planet gear wheels i4 rotatably mounted on a stationary gear support plate 14b, the worm wheel 11 drives a toothed crown 15 of the planet gear which in turn is keyed on a vertical, double take-off, centrally journalled drive shaft 16. Planet gear wheels 14 are rotatably mounted on shafts 14a. which are secured in fixed position on the support plate. When hollow shaft 13 rotates with gear wheel 12 the planet gear wheels 14 are forced to rotate and since they are in fixed positions the toothed crown and thereby shaft 16 are caused to be rotated about planet wheels 14. The double take-off drive shaft 16, in addition to driving the mixing tools, drives a cable drum 17 which is mounted on the lower end of the shaft with the interposition of suitable clutch and braking members and is adapted to drive the charging hoist of the mixing device or any other conveying apparatus, such as for the removal of the mixed concrete from the chamber. The clutch and brake devices are operated by way of a manually displaceable lever 18.

At its upper end the shaft 16 is connected to structure including the arms 15 supporting the mixing devices 4, and consequently the toothed crown 15 which is driven by the speed reducing planet gear wheels 14, drives the shaft 16 and with it the arms 3 and mixing devices 4 at reduced speed. It will be apparent that the speed at which the mixing devices 4 are driven is considerably reduced with respect to the speed of drive shaft 8 because the speed is not only reduced by way of the worm wheel 11 but also by the planetary gear drive 12, 14, 15.

As may be seen, the entire driving unit may be dismantled in a very short time and replaced by an alternative driving unit, so that if the driving gear breaks down, which may happen very frequently when working on sites under the aforementioned difficult conditions, the time lost by breakdowns involving repairs and exchanges may be reduced to a minimum. in addition the driving gear mechanism of the present invention is suitable, without the inter-position of any other means involving an increase in the cost of the plant, for driving the charging hoist of the mixing apparatus. Finally, in the entire arrangement, care is taken to ensure that any desired source of power may be used to drive the mixing apparatus. In conclusion the driving gear mechanism also simultaneously constitutes the support for the revolving mixing devices, a feature which represents a further simplification and reduction in cost of the entire construction of the mixing apparatus.

Having now described our invention with reference to the embodiment shown, we do not wish to be limited thereto, but what we desire to protect by Letters Patent of the United States of America is set forth in the appended claims.

We claim:

1. A mixer for concrete or the like comprising, in combination, a vertically disposed annular mixing chamber defined by a supporting plate and inner and outer generally cylindrical walls mounted on said supporting plate, said inner wall enclosing a center space, a gear support plate or the like mounted proximate the lower end of said inner wall, a drive shaft having an upper portion disposed in said center space centrally of said inner wall and a lower portion extending below said gear support plate, radially extending means connected to the upper end of said driven shaft and rotatable therewith and mixing devices operatively connected to said radially extending means and extending downwardly therefrom to said supporting plate for movement along a circular path, a reduction gear for driving said driven shaft including gear wheels mounted on stationary shafts on said gear support plate, means including a toothed crown operatively connecting said gear wheels to said drive shaft and a hollow shaft disposed around said drive shaft, said hollow shaft having secured thereto a driving gear meshing with said gear wheels and having a driven portion disposed below said gear support plate, and an external source of power including drive means meshing with said driven portion, said drive shaft, said driving gear of said hollow shaft, said gear Wheels and said toothed crown being supported as a driving unit in said center space above said support plate.

2. A mixer for concrete or the like comprising, in combination, a vertically disposed annular mixing chamber defined by a supporting plate and inner and outer generally cylindrical walls mounted on said supporting plate, said inner wall enclosing a center space, a gear support plate or the like mounted proximate the lower end of said inner wall, a double take-off drive shaft having an upper portion disposed in said center space centrally of said inner wall and a lower portion extending below said gear support plate, radially extending means connected to the upper end of said driven shaft and rotatable therewith and mixing devices operatively connected to said radially extending means and extending downwardly therefrom to said supporting plate for movement along a circular path, a reduction gear for driving said driven shaft including gear wheels mounted on stationary shafts on said gear support plate, means including a toothed crown operatively connecting said gear wheels to said drive shaft and a hollow shaft disposed around said drive shaft, said hollow shaft having secured thereto a driving gear meshing with said gear wheels and having a driven portion disposed below said gear support plate, and an external source of power including drive means meshing with said driven portion, said drive shaft, said driving gear of said hollow shaft, said gear wheels and said toothed crown being supported as a driving unit in said center space above said support plate and means connected to said lower portion of said drive shaft for driving a hoist or the like at the reduced speed of said drive shaft, said toothed crown being in meshing engagement with the teeth of said gear wheels and keyed to said drive shaft.

3. A mixer for concrete or the like comprising, in combination, a vertically disposed annular mixing chamber defined by a supporting plate and inner and outer generally cylindrical walls mounted on said supporting plate, said inner wall enclosing a center space, a gear support plate or the like mounted proximate the lower end of said inner wall, a double take-off drive shaft having an upper portion disposed in said center space centrally of said inner wall and a lower portion extending below said gear support plate, radially extending means connected to the upper end of said driven shaft and rotatable therewith and mixing devices operatively connected to said radially extending means and extending downwardly therefrom to said supporting plate for movement along a circular path, a reduction gear for driving said driven shaft including gear wheels mounted on stationary shafts on said gear support plate, means including a toothed crown operatively connecting said gear wheels to said drive shaft and a hollow shaft disposed around said drive shaft, said hollow shaft having secured thereto a driving gear meshing with said gear wheels and having a driven portion disposed below said gear support plate, and an external source of power including drive means meshing with said driven portion, said drive shaft, said driving gear of said hollow shaft, said gear Wheels and said toothed crown being supported as a driving unit in said center space above said support plate and means connected to said lower portion of said drive shaft for driving a hoist or the like at the reduced speed of said drive shaft, said toothed crown being in meshing engagement with the teeth of said gear wheels and keyed to said drive shaft, said driven portion of said hollow shaft being a worm wheel and said source of power being disposed radially outwardly of said gear support plate and having a worm gear meshing with said worm wheel.

References Cited in the file of this patent UNITED STATES PATENTS 1,363,560 Browne Dec. 28, 1920 Buehler July 21, 1925 Sturtevant Apr. 12, 1932 Beardsley et al June 24, 1941 Pierce June 2, 1942 Brown June 5, 1945 Fejmert Sept. 6, 1955 Miller Dec. 9, 1958 FOREIGN PATENTS France May 21, 1909 France Mar. 17, 1950 

